The objective is to study the growth and function of cultured human endothelial cells (EC) isolated from diverse vascular sites in different aged donors of both sexes. Emphasis will be placed on examining proliferative potential, selected metabolic activities, certain transport functions, and membrane properties related to hemostatic function. Vascular tissue will be obtained from different sites in brain-dead, heart-beating cadavers, and large vessel and capillary EC will be isolated. Primary, secondary and cloned EC cultures will be generated and distributed to the component projects. The following goals will be pursued: determine the in vitro lifespan of EC; examine cytogenetic properties of EC; investigate the roles of and cooperative interactions between various culture components as they affect human EC growth in Phase II and Phase III cells from young donors and Phase II cells from older donors; measure the metabolites of arachidonic acid synthesized by human EC; characterize and quantify human EC interaction with Factor VIII-related antigen and other coagulation components; and measure vesicular ingestion capacity and insulin binding in human EC and examine the effect of different collagen substrata on these EC functions.